$highlight-color: #f90;
$basic-border: 1px solid black;
#app{
    color:$highlight-color ;
    border: $basic-border
}
$nav-color: #F90;
nav {
  $width: 100px;
  width: $width;
  color: $nav-color;
  background-color: black
}
#content {
    article {
      h1 { color: #1dc08a }
      p {  font-style: italic; }
      a {
        color: blue;
        &:hover { color: red }
      }
    }
    aside { background-color: #f90 }
  }